Principles and characteristics of common adsorbents (activated carbon, molecular sieve, silica gel, activated alumina)

1. Overview of the adsorption and separation process Adsorption means that when a fluid (gas or liquid) is in contact with a solid porous substance, one or more components in the fluid are transferred to the outer surface of the porous substance and the inner surface of the micropores to be enriched on these surfaces to form a monolayer or multiple molecules Layer process. The adsorbed fluid is called adsorbate. Due to the different physical and chemical properties of adsorbate and adsorbent, the adsorption capacity of adsorbent for different adsorbates is also different. Therefore, when the fluid is in contact with the adsorbent, the adsorbent will affect one of the fluids. Or some components have higher adsorption selectivity compared to other components, and the components of the adsorption phase and the resorbance phase can be enriched, so as to realize the separation of substances. 2. The adsorption/desorption process Adsorption process: It can be considered as a process of concentration or liquefaction. Therefore, the lower the temperature and the higher the pressure, the greater the adsorption capacity. For all adsorbents, the more easily liquefied (the higher the boiling point), the greater the amount of gas adsorbed, and the less likely to liquefy (the lower the boiling point), the lower the amount of gas adsorbed. Desorption process: It can be considered as a process of gasification or volatilization. Therefore, the higher the temperature and the lower the pressure, the more complete the desorption. For all adsorbents, the gas that is more easily liquefied (the higher the boiling point) is less likely to be desorbed, and the gas that is less likely to be liquefied (the lower the boiling point) is, the easier it is to desorb. Adsorption is divided into physical adsorption and chemical adsorption. The principle of physical adsorption separation: use the difference in the adsorption force (van der Waals force, electrostatic force) between the atoms or groups on the solid surface and the foreign molecules to achieve separation. The size of the adsorption force is related to the properties of both the adsorbent and the adsorbate. The principle of chemical adsorption separation: based on the adsorption process that chemical reactions occur on the surface of the solid adsorbent to combine the adsorbate and the adsorbent with a chemical bond, so the selectivity is strong. Chemical adsorption is generally slow, can only form a monolayer and is irreversible. 3. characteristics of different adsorbents Activated carbon: It has a rich microporous and mesoporous structure, the specific surface area is about 500-1000m2/g, and the pore size distribution is mainly 2-50nm. Activated carbon mainly relies on the van der Waals force generated by the adsorbent to produce adsorption, and is mainly used for adsorption of organic compounds, adsorption and removal of heavy hydrocarbons, deodorants, etc.; Molecular sieve: It has a regular microporous pore structure with a specific surface area of ​​about 500-1000m2/g, mainly micropores, with a pore size distribution between 0.4-1nm. The adsorption characteristics of molecular sieve can be changed by adjusting molecular sieve structure, composition and type of balance cation. Molecular sieves mainly rely on the characteristic pore structure and the Coulomb force field between the equilibrium cations and the molecular sieve framework to produce adsorption. It has good thermal and hydrothermal stability. It is widely used in the separation and purification of various gas and liquid phases. When used, the adsorbent has the characteristics of strong selectivity, high adsorption depth and large adsorption capacity; Silica gel: The specific surface area of ​​silica gel adsorbent is about 300-500m2/g, mainly mesoporous, with a pore size distribution of 2-50nm, and the internal surface of the pore channel has abundant surface hydroxyl groups, which are mainly used for adsorption drying and pressure swing adsorption for CO2 production, etc.; Activated alumina: specific surface area 200-500m2/g, mainly mesoporous, pore size distribution in 2-50nm, mainly used in dry dehydration, acid waste gas purification, etc.

What is carbon molecular sieve?

carbon molecular sieve - Adsorbent for metal heat treatment, etc. Carbon molecular sieve is a new type of adsorbent developed in the 1970s. It is a kind of excellent non-polar carbon-based cellulose material. Carbon Molecular Sieves (CMS) is used for separation and enrichment of air. Nitrogen adopts a normal temperature and low pressure nitrogen production process, which has the advantages of less investment cost, faster nitrogen production speed, and lower nitrogen cost than the traditional cryogenic high pressure nitrogen production process. Therefore, it is currently the preferred pressure swing adsorption (PSA) nitrogen-rich adsorbent for air separation in the engineering industry. This nitrogen is used in the chemical industry, oil and gas industry, electronics industry, food industry, coal industry, pharmaceutical industry, cable industry, and metal It is widely used in heat treatment, transportation and storage. R & D background In the 1950s, with the tide of the industrial revolution, the application of carbon materials became more and more extensive. Among them, the application field of activated carbon was PSA carbon molecular sieve for nitrogen production. The expansion is the fastest, from the initial filtration of impurities to the separation of different components. At the same time, with the advancement of technology, mankind's ability to process materials has become stronger and stronger. In this case, carbon molecular sieves have emerged. Main components of carbon molecular sieve The main component of carbon molecular sieve is elemental carbon, and the appearance is a black columnar solid. Because it contains a large number of micropores with a diameter of 4 angstroms, the micropores have a strong instantaneous affinity for oxygen molecules and can be used to separate oxygen and nitrogen in the air. The pressure swing adsorption device (PSA) is used in industry to produce nitrogen. Carbon molecular sieve has large nitrogen production capacity, high nitrogen recovery rate and long service life. It is suitable for various types of PSA nitrogen generators and is the first choice for PSA nitrogen generators. Carbon molecular sieve air separation nitrogen production has been widely used in petrochemical, metal heat treatment, electronics manufacturing, food preservation and other industries. working principle Carbon molecular sieve uses the characteristics of sieving to achieve the purpose of separating oxygen and nitrogen. When the molecular sieve adsorbs impurity gas, the macropores and mesopores only play the role of channels, transporting the adsorbed molecules to the micropores and submicropores, and the micropores and submicropores are the real adsorption volume. As shown in the previous figure, the carbon molecular sieve contains a large number of micropores. These micropores allow molecules with a small dynamic size to rapidly diffuse into the pores while restricting the entry of large-diameter molecules. Due to the difference in the relative diffusion rate of gas molecules of different sizes, the components of the gas mixture can be effectively separated. Therefore, when manufacturing carbon molecular sieves, according to the size of the molecules, the distribution of micropores inside the carbon molecular sieve should be 0.28 to 0.38 nm. Within the size range of the micropores, oxygen can quickly diffuse into the pores through the pores of the micropores, but it is difficult for nitrogen to pass through the pores of the micropores, thereby achieving oxygen and nitrogen separation. The pore size of the carbon molecular sieve is the basis for the separation of oxygen and nitrogen. If the pore size is too large, oxygen and nitrogen molecular sieves can easily enter the pores and cannot separate; and if the pore size is too small, neither oxygen nor nitrogen can enter. In the micropores, there is no separation effect.   SLCMS-USP | Carbon Molecular Sieve PSA Nitrogen Equipment SLCMS-HP1 3A Molecular Sieve We are carbon molecular sieve,If you are interested in carbon molecular sieve,You can browse related products and initiate consultations on our website.

The difference between 3a, 4a, 5a molecular sieves

The difference between 3a, 4a, and 5a molecular sieves is mainly due to the different uses, such as the difference in bulk density and compressive strength. Many people who do not understand will think that the difference between these different molecular sieves is in diameter. In fact, this is wrong. Let’s compare the differences and similarities of these three molecular sieves. 3A molecular sieve The bulk density is 680Kg/m³, and the compressive strength (N)≧80/P. Mainly used in the drying of petroleum cracking gas, olefin, gas training field, oil field equipment, and industrial dryer for chemical industry, medicine, hollow spirit, etc. 4A molecular sieve The bulk density is 680Kg/m³, and the compressive strength (N)≧80/P. Mainly used for the drying of natural gas and various chemical gases and liquids, refrigerants, medicines, electronic materials, and abnormal substances. 5A molecular sieve , The bulk density is 680Kg/m³, the compressive strength (N)≧80/P. Mainly used for natural gas drying, desulfurization, carbon dioxide removal, nitrogen and hydrogen separation, production of oxygen, nitrogen and hydrogen, petroleum dewaxing, etc. Molecular sieve has 3A/4A/5A/10X/13X and other models, each model has diameters of 0.4-0.8mm, 1-2mm, 1.6-2.5mm, 2-4mm, 3-5mm and 4-6mm. Molecular sieve.

What is 4A molecular sieves?

4A molecular sieves The selective adsorption performance of water is higher than any Other molecules. It is one of the most used molecular sieve varieties in industry. 4A molecular sieve is an alkali metal aluminosilicate that can adsorb water, NH3, H2S, sulfur dioxide, carbon dioxide, C2H5OH, C2H6, C2H4 and other molecules with a critical diameter not greater than 4A. It is widely used in the drying of gases and liquids, and can also be used in the refining and purification of certain gases or liquids, such as the production of argon. .content_box { border: 1px solid #333; padding: 20px; } .content_box img { max-width: 100%; height: auto; } .content_box h3 { text-align: center; } SLCMS-G1.3 | molecular sieves | Molecular Sieves Supplier Cms Carbon Molecular Sieve SLUHP-100 SLCMS-USP | Carbon Molecular Sieve We are Top Quality 4a Molecular Sieves,If you are interested in 4A molecular sieves,You can browse related products and initiate consultations on our website. { "@context" : "", "@type" : "Article", "headline": "What is 4A molecular sieves", "image":"", "name" : "What is 4A molecular sieves", "author" : { "@type" : "Person", "name" : "ShanLi", "url": "" }, "datePublished" : "2021-10-23", "articleSection" : "4A molecular sieves", "articleBody" : "The 4A molecular sieve has a pore size of 4A, which absorbs water, methanol, ethanol, hydrogen sulfide, sulfur dioxide, carbon dioxide, ethylene, and propylene. It does not adsorb any molecules larger than 4A in diameter (including propane). The selective adsorption performance of water is higher than any Other molecules. It is one of the most used molecular sieve varieties in industry.", "url" : "" }

Introduction of molecular sieve material

In the context of carbon neutrality, molecular sieves, a new material for adsorption and catalysis, have gradually attracted attention. A few days ago, at the 7th Molecular Sieve Technology and Application Summit Forum of Jianlong Micronano, more than 200 guests including China Gas Industry Association and heads of well-known domestic gas equipment companies gathered to discuss the application of molecular sieves in the energy, chemical industry and environmental fields. Molecular sieve adsorbents screen the carbon dioxide, nitrogen and other components in the air through physical adsorption, so as to achieve the purpose of purifying the target gas. Because molecular sieve has the advantages of high adsorption capacity, strong selectivity, and high temperature resistance, it has been widely used in many fields such as petrochemical industry, coal chemical industry, air separation and purification, environmental management and so on. At present, there are four major paths for feasible carbon neutral technologies, namely, energy transition, carbon capture and utilization, low-carbon life, and plant carbon sink. Liu Yingshu, director of the Institute of Gas Separation Engineering, University of Science and Technology Beijing and director of the Group Standards Committee of the China Gas Association, introduced at the forum that the above-mentioned technical paths can be found in the application of molecular sieves. In terms of carbon capture and utilization, molecular sieve adsorbents and catalysts are used to collect and store carbon dioxide, so as to achieve industrial carbon emission reduction and utilization; in terms of plant transformation, zeolite water-retaining agents and repair agents are used to fix water for soil moisturizing and repair, so as to achieve deserts. Fixed water afforestation, saline-alkali land restoration, etc. Data shows that steel plants across the country need a total of 130,000 tons of molecular sieve for oxygen production each year. In addition, in the field of hydrogen production, molecular sieves can not only be used for the recovery and purification of hydrogen in various industrial hydrogen-containing tail gas, but also help to reduce environmental pollution caused by tail gas emissions or direct combustion of tail gas. In addition to the above fields, molecular sieves also play an important role in the utilization of nuclear energy. According to Liu Zhihui, director of the Nuclear and Radiation Safety Center of the Ministry of Ecology and Environment of China, as an inorganic ion exchanger, molecular sieves have the advantages of high radiation resistance, mechanical, thermal and ionization stability. Molecular sieves were used in the treatment of radioactive waste water in the nuclear accident at the Fukushima nuclear power plant in Japan, and good results have been achieved. It is predicted that with the continuous growth of the oil and gas industry in emerging economies, the compound annual growth rate of the global molecular sieve market from 2020 to 2025 will be 5.65%, and it will reach 4.39 billion US dollars in 2025. On this subdivision track, there are already some listed companies with considerable strength. Molecular Sieve Material

Features of portable nitrogen generator

There is cryogenic nitrogen production, which uses low temperature to turn all the air into a liquid state, and then uses the different boiling points of different components of the gas to separate in the process of heating. The characteristics are: relatively large scale, relatively high purity, and large area. Long start-up time; Nitrogen production at room temperature is the use of adsorbents to separate oxygen and nitrogen in the air. The characteristic is that it requires a certain pressure, which occupies a small area, has a fast start-up speed, is small in scale, and has relatively low purity. Portable Nitrogen Generator